Burning of fuel



May 28, 1929.

H. KREISINGER BURNING OF FUEL Filed Oct;

INVENTOR 'M ATTORNEY5 I Patented May 28, 1929.

UNITED STAT ES PA rEN `o FcE..-"

HENZRY KREISINGER, OF PIERMONEILNEW YORK, SSIGNOR TO COMBUSTION ENGI- A NEERING CORPOBATION, NEW YORK, N. Y A: CORPQRATION OF NEW- YORK.

BURNING OF FUEL.

O :Application filed October -11, 1924. Serial No. ?42,976."

My invention relates to the burning of'fuel on grates and in suspension, and especially to the burning of fuel in both' ways concurrently. In doing this, I ain to obviate or remedy various d'rawbacks of either method alone: e. g., to avoid all dificulty from slagging in the case of powdered fuel, for exam-` ple, to reduce 'the percentage of uncombned' oxygen in the'products of combustion from o thefuel on the grate; and to mprove the efiiciency of conibustion over what is ordinarily attained by either method alone. My invention is especially aclvantageous in the burning of relatively coarsely pulverized grate fuels, such as No. 4 buckwheat, eulm or slush for 'example. nectio n with autonatic stokers; and 'I have hereinafter explained it with special reference to such a mode of use. i

In the drawing, Fig. l shows a vertical sec`- tion througha steam boiler powdered fuel furnace, equipped with 'a Coxe stoker.

Fig. 2 shows across-section .through one of the travelling grate members, on a larger scale than F ig. l. i

In Fig. l is shown a water tube boiler of familiar type, coniprising a t'ransverse drum 10 connected to approximately upright front and rear headers 11,12. These headers-11, 12 are themselves interconnected by banks of fore and aft water tubes 13, inclined upward toward the rear,-speaking of front and rear in reference to the regions where the powdered fuel nozzles are located and whence the products of combustion make exit from its main eo'mbustion space or chamber 15, respeci tively. The water tubes 13 overlie an opening in, the top or roof 16 of the combustion chamber 15, and the furnace gases take a cir-` 10 .cuitous course among them (as purtly defined by the bafiling 17, 18, 19) on their way to the stack.

As shown in Fig. 1, the combustion Chams ber proper at lis a large, deep, unobstructed chamber enclosed by walls which slope outward slightly, sothat the ehamber as a whole expands upwardly.. Powdered fuel preferably with somewhat more than carrying ar is fed in through one or more downwardly directed burners 25 mounted in the roof lnear the front wall 26, and is continually ignited by the heat of the 'latter and of the furnace. Air additional to that entering at the burner 25 is (or may be) supplied through damper controlled inlet-openngs 27 at various heights Itis Convenientlyapplicable in con in the front wall 26. The burning 'stream of niingled 'air, powdered fuel, comhustible .gases from the fuel, and products of combuston) descends in the front of the chamber 15 until its monentum is overcome by the upward draft through the hoiler. It then bends rcarward and ascends, and finally passes from the conbustion chanber to the rear (upper) pass of the boiler as already described,-'all about as indicated bythe arrows. The size of the chamber 15 and the contiguity of the` unbaflied downward and upward fuel streams and their change of direction as described assure rapid and complete' combustion in the chamber 15.

At the bottom of the chamber 15, fuel, such 'as nentioned above, is burned by .means of any suitable grate 'or stoker, here shown as 'a travelling grate stoker 30 of theCoxe type'.

The active upper 'run of the' stoker 30 travels from the rear toward the front, and the fu'el is supplied thereto at the rear, as diagrammatically indicated at 31. -On its way from the rear to the front, .the fuel passes through' the various stages of combustion i'n suecession and is completely burned.- Thefinal residue of ash passes under the water back 32 at the bottom of the front wall 26' andis discharged (as shown) as the grate 30 makes its front turn at 33. Air for combustion of the fuels supplied through the grate 30. For this purpose, a sheet metal casing 34 with a plurality of pressure compartments 35, 36, 3?, 38 is arranged between the upper and .lower runs of the grate 30. The fuel supporting netal bars or keys 39 of the stoker '30 have a multiplicity of air holes or jet openngs 4- l through them, and the tops of the chambers 35, 36, 37, 38 are open, so that the air from these chambers is diseharged throu h the holes inamulti-` plcity of j ts. V Prefera ly, the holes 41 slope upward to the rea`ras shown, so that the air jets from them are correpondingly directed.

The'air thus supplied not only naintains combustion of`the fuel on the grate 30, but also cools the grate and protects it .from burning out.` The airpressure in the several chambers 35,.36,- 37, 38 is regulated according to the requiremeits of the ful in'ts variouslstages of combustion from the rear to the `-front of the furnace. i

Preferably, the total amount of airsupplied through the grate 30,is .so.ne`what in excess of that required for complete combustion of-the :fuel thereon, 'so thaft the' surplus may assist in--the combustion of the superjacent pulverize'd fuel stream. As the'pulverized fuel stream .passes rearward across the fuel bed n the grate 30, the rearwardinelined air and flame jets from the fuel' bed strike it convergently, and are deflected rearward by it. As a result, a series of eddies is set up along the lower edgeof the pulverized fuel stream, thu's assuring thorough intermixture of the air with the fuel and burning gases, and prom'oting complete combustion. 4

Besides the inter-'action between the fuel bed on the grate and the pulverizcd fuel i stream as regards combustion, important advantage ssecured n respect of the incombustible residue or ash f'om'the pulVerized fuel. This `relati vely 'heavy residue continua'lly fallsupon the fuelbed on the travelling grate 30, and is continually carried 'along and 'diseharged bythe 'grate with the. ash from the combustion of' the fuel birned thereon.- Toward the front of the furnace, where combustion on the grate 30 has been completed, the jets of ai -passing through the grate cool the ash from' both sources below slagging temperature, and prevent it from runnng together into a solid mass. This obviates all neces- -sty for' mantanng a cooling zone n the i combustion, or'bv any other "means,.-so .that

lower region of the combustion chamber 15,-

whether by a water screen, or by admission of air in excess of that requird for complete the percentage of air in the atack gases is less,

anith temperature of the 'products of combustion as they enterthe boiler isgreater.

By the invention, small sizesof coal may be fed with the pulverized coal so thata large proportion of the fuel may be fed to' theburners. Also of coals having low.. ash and highashcontent, only the low ash rade deal need be pulverize'd, the other being urnt on thegrate.

I claim:

1. The method of burnin fuel on a travel-- ling grate and ,pulverized uel in suspension in a. common combustion chamber with exit for products of combustion from its upper rear region, which method comprises directin; powdered fuel stream` downward in the f'ntof the-combustion chamber, and blowing air upward through the moving fuel bed in 'earivrd-inclined jets.

2. A combined lump and powdered fuelburning furnace comprising a travelling grate and a combustion chamber thei-cover with exit for products of combustion at the rear and means for introducing a dowmvnrcl di'ected fuel stream into the front thereof,

and means for blowing air upward through the fuel bed in rearward-nclncd ets.

A combined lunp fuel and' powdered fuel burning fUI'IRH'O conprising a travelling grate adaptedto, receive fnel at the rear and progress it forward as it burns, and a com- 'bustion'chamber thereover with exit for p'rodi ucts of combustion at the real' and means for introducinga downward directcd fuel stream into the front thereof, an'd means for blowing air upward through the fuel bed in rear ward-inclined j et-s.

4. The method of burning powdered and coar'sefuel in a common combustion chamber, which comprises moving a bed of coarse fuel forwardly in the chamber, directing a stream of powdered fnel over said fuel bed in a gem-- eral rearwar'd direction, blowing air through the bed ina rearward direction, and drawing 4 off the productsof combustion at the rear.

5. The method, of burning coarse fuel on.

a grate and powdered fuel in a common combustion ehamber `with exit for products of `combustion in its upper region, which method 

